Process for inhibiting diketene polymerization

ABSTRACT

A process for inhibiting the polymerization of diketene in storage which comprises adding water to the diketene in amounts of from about 0.001 to about 2 weight percent.

United States Patent 1 Jacobs et al.

[451 Sept. 18,1973

PROCESS FOR INHIBITING DIKETENE POLYMERIZATION inventors: Max LeRoyJacobs, Livermore,

Colo.; Buster Watson Higdon, Pampa, Tex.

Assignee: Celanese Corporation, New York,

Filed: Mar. 19, 1971 Appl. No.: 126,301

Related U.S. Application Data Continuation of Ser. No. 628,835, April 6,l967, abandoned.

U.S. Cl. 260/3433 Int. Cl C07d 3/00 Field of Search 260/3439 PrimaryExaminer- Alex Maze] Assistant Examiner-Anne Marie T. Tighe [57]ABSTRACT A process for inhibiting the polymerization of diketene instorage which comprises adding water to the diketene in amounts of fromabout 0.00l to about 2 weight percent.

3 Claims, No Drawings 3 PROCESS FOR INHIBITING DIKETENE POLYMERIZATIONThis is a streamline continuation of US. Pat. application Ser. No.628,835, filed Apr. 6, 1967, and now abandoned.

BACKGROUND OF THE INVENTION This invention relates to stabilizeddiketene and to a process for inhibiting the polymerization of diketenein storage.

Diketene is a very unstable compound which tends to polymerize whenstored. Such polymerization destroys its usefulness in such areas as thepharmaceutical industry where it is used in the synthesis of drugs.Various about 0.5 to 1.80 weight percent based on the total weight ofthe diketene material. I

The water may be added to the diketene by any conattempts have been madein the past to minimize this ti l means, how v r, it is preferable thatthe polymerization of diketene but they have been either t r b di d h hlthroughout h dik ineffective or have impaired the purity of the diketeneten which precludes its use in such areas as the drug indus- In theabsence of indications to the contrary all protry. The methods used inthe past to inhibit polymerizaportions and concentrations of materialare expressed tion of diketene have included refrigeration, andaddherein on a weight basis. ing boric acid or hydrosulfatcs of weakbases such as The invention is additionally illustrated by thefollowcopper sulfate to the diketene. U. S. Pat. No. 3,271,420 ingexamples: to Zima discloses a method for stabilizing diketene by addingelemental sulphur to it. However, the sulphur EXAMPLE 1 remains in thediketene and must be removed by distil- Diketene samples, to which 1%water was added, lation or other methods if purity is important to theultiwere stored in 5 gallon containers at 77 and 38F, remate use of thediketene. spectively, and allowed to stand for varying lengths of time.SUMMARY The samples were periodically tested for color using It has nowbeen found that the polymerization of diplatinumcobalt APHA (Hazen)color standards on a ketene in storage may be inhibited withoutimpairing its Beckman Model DU Spectrophotometer. The higher purity byadding water to the diketene in amounts of numbers represent a darkercolor which indicates infrom about 0.001 to about 2 weight percent,based on creased polymerization of diketene. The data taken the weightof the diketene. from the water inhibited sample was compared with aAccordingly, it is an object of this invention to prO- control samplecontaining no water. Results shown vide a process which is effective ininhibiting the polybelow in Tables I and 11 indicate a significantretardamerization of diketene in storage. tion of diketenepolymerization in those samples con- Another object of this invention isto provide a protaining 1 percent water as an inhibitor. The color ofthe cess which inhibits the polymerization of diketene but blank orcontrol sample was too dark to permit a nuwhich requires no subsequentdistillative procedures to merical reading, which reflected anexceptionally high insure the purity of the substance. degree ofdiketene polymerization.

TABLE I (38 F.)

Days stored APHA color standards Control Dark Dark Dark Dark Dark Darkorange. orange. orange. orange. orange. orange. 1% H2O added- 70 120 120120 DESCRIPTION OF THE PREFERRED TABLE II (77 F.)

EMBODIMENT Days stored Since the formation of polymers within diketeneis 21 2s 35 42 accompanied by a change in the color of the substance,APHA color Standards the darker color indicating a ig degree P P ymCommi Dark Dark Dark Dark ization, the maintenance of a lighter color inthe dtkeorange. orange. orange. orange. tene is evidence of theinhibitory effect of the water. 1% H2O added 8 16 22 22 While noparticular conditions of temperature or pres- EXAMPLE 11 sure arenecessary to insure this inhibiting effect, the water is particularlyeffective as an inhibitor at the temperatures at which diketene isnormally stored, which is between 38 and 77F.

Analysis of commercial diketene discloses a small percentage of aceticanhydride and acetic acid present shown below in Table [11 indicatesthat the addition of 5 a small percentage of water inhibits thepolymerization of diketene when the acetic anhydride present in thediketene is first hydrolyzed to acetic acid.

TABLE III( 77F) Days stored Apha Color Standards Acetic anhydride 3 lhydrolyzed 2% 33 excess H 0 Control 6 600 The principle, preferredembodiment, and mode of operation of the present invention has beendescribed in the foregoing specification.

What is claimed is:

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

l. A method for inhibiting the polymerization of diketene in storagewhich consists of incorporating water into said diketene in an amountstoichiometrically sufficient to hydrolyze any acetic anhydridecontained in said diketene and to provide, in addition, an excess ofwater amounting to about 0.001 percent to about 2 percent by weightbased on the weight of the diketene.

2. The method of claim 1 wherein the diketene before addition of thewater contains from about 0.5 to about l.8 percent of acetic anhydrideby weight.

3. The method of claim 2 wherein the diketene is maintained at atemperature between about 38F and about 77F.

2. The method of claim 1 wherein the diketene before addition of thewater contains from about 0.5 to about 1.8 percent of acetic anhydrideby weight.
 3. The method of claim 2 wherein the diketene is maintainedat a temperature between about 38*F and about 77*F.